The appointment of Mr Leung leaves a vacancy for the position of Education Commission chairman, the Government's think-tank on education policy.
Since taking up the role in 1998, Mr Leung has become Tung Chee-hwa's top adviser on education and the architect of the far-reaching reform blueprint.
Yesterday, legislator Cheung Man-kwong and academics said it would be better to appoint an Executive Councillor as the new chairman.
"An Exco member has the political clout to deal with government officials, legislators and university heads," he said.
"A series of reform proposals recommended by the commission are being implemented and an influential figure is needed to oversee smooth implementation and rectify deviation from the direction of reform."
He said Rosanna Wong Yik-ming and Henry Tang Ying-yen, both Executive Councillors, were possible candidates.
Anthony Cheung Bing-leung, associate professor in the Department of Public and Social Administration at City University, agreed that Ms Wong, executive director of the Hong Kong Federation of Youth Groups, would be an ideal successor. But Ms Wong would not comment on such speculation, her assistant said.
Cheung Kwok-wah, associate dean of the Faculty of Education at the University of Hong Kong, said it was likely the Government would prefer a figure outside the education sector to avoid any conflict of interest.
"It's rather difficult, however, to find a person who is interested in education and has a high social standing to take up the post," said Mr Cheung, who is also a member of the Education Reform Liaison Team, a government-appointed committee overseeing the implementation of education reform. It is understood that senior education officials have also acknowledged it will be tough to replace Mr Leung.